(1) Field of the Invention
This invention relates to a method and apparatus for interactively generating a display signal.
(2) Description of the Related Art
Traditional TV broadcast is characterised by temporal synchronisation for all viewers, ignoring the small differences in transit times of the signal due to differences in transmitter to user distances. Therefore at the moment of broadcast all viewers receive the same, uniform signal substantially instantaneously. Interactive forms of the medium, such as Two Way TV, Web TV are generally characterised by providing the viewer with the facility to interact with a designated interactive area of the TV screen. This may utilise a split screen in which the interactive area may have internet information, an on screen menu, or information which may be relevant to the main broadcast part of the TV screen. These systems are characterised by presenting information in response to the user's interaction within a fixed predefined interactive area of the screen.
In contrast to the limited interaction with TV broadcast on current systems, computer games consoles (eg. Sony Playstation, Sega Saturn, Nintendo 64) are presented to the viewer on TV screens or dedicated display screens, but each viewer has the ability to achieve unique interaction with the imagery/sounds presented on the TV, which are processed by the games console using computer technology, in response to the users actions. Generally the user's perceived TV environment (including images, sounds and other sensory signals) are produced by computer generation within the games console, which may or may not also utilise digitised predefined data, such as sounds in the TV environment which shall be referred to as the computer generated environment (CGE) or in the specific case of images, computer generated imagery (CGI). These games consoles and the CGE are characterised by high frequency update rate, typically in excess of 25 frames per second or 25 Hz. This gives the impression of instantaneous or real time response to the user's actions and also a smooth and seamless dynamic image. The individual frames are not discernible as individual frames, but rather contribute to the overall real time dynamic environment, giving the impression of real time control and interaction with the CGE.
It is desirable that the real time CGE is as realistic as possible, and greater degrees of realism are generally achieved by increased computer processing power and by using the most efficient representation in terms of realism versus processing power. By way of example only, one of the most efficient representations for CGI uses relatively coarse polygonal or faceted geometric model in which the greatest detail in terms of polygon distribution would generally be used in the more geometrically complex areas. By a process known as texture mapping, in which photorealistic textures representing surface features are mapped onto the individual polygon faces, a relatively realistic CGI is achieved notwithstanding the relatively coarse polygonal geometry representation. The product of the number of texture mapped polygons in the CGI and the image update rate measured in frames per second yields a number defining the number of texture mapped polygons the computer processing is required to process per second, which may be 1,000,000 polygons per second.
We have identified that the level of interaction offered to the viewers of interactive broadcast TV is limited, and this consequently limits the applications of such medium. Furthermore we have identified that although the interaction of a games console is greater than interactive TV, the actual theme of the CGE is limited to the specific game content loaded into the console, for example via CD ROM, cartridge, the internet or broadcast to a TV with the appropriate hardware to run CGE type games or by other means.